There just seems to be a misunderstanding on the intention of a though experiment here. There is a subtle implication that because the thought experiment is "contrived" that its less valuable.
When thinking about philosophy, a core part of philosophy is to reduce concepts, ideas, or beliefs into abstractions (or a "spirit" or "essence" of what their intention is), the thought experiment presents itself as a perfectly useful tool to help challenge those concepts.
Ethics is not about absolutes, but really about sussing out where gray areas exist in what some might believe are black and white situations. Additionally, most of the scenarios are presented as a thought experiment, because conducting a real experiment with those conditions would be wildly _un_ethical.
How are we supposed to determine the nuance of valuing human life if we were bound to doing actual experiments? Also, who in their right mind would conduct such as experiment?
Zimbardo faced enough flack testing the limits of obedience and authority in the Standford Prison Experiement.